I've visited all of the NPS units in California, Nevada, Utah, Montana, Wyoming, Colorado, Arizona, and New Mexico. I've been to others in many states well. Geographically, the Rocky Mts. and West Coast units tend to be the most interesting.
I always count on a National Parks Service Visitor Center to provide a combination of logistics, nature education, and historical context. I have an informal goal to visit as many parks as possible. This page is for NPS enthusiasts like me, or anyone interested in the natural world and our nation's heritage.